Light emitting diodes or LEDs are constantly being further developed with regard both to their light output and energy efficiency and their price. It can be foreseen that they will also be put to widespread use for illumination purposes.
In contrast to conventional illumination means such as incandescent light bulbs and fluorescent tubes, light emitting diodes can be modulated very rapidly. They are therefore superbly well suited for data transmission in parallel with illumination.
It is known, to use a light emitting diode for room illumination—that is, as a lamp—simultaneously for transmitting analog and/or digital data by modulating the intensity of the light emitting diode. It is suitable to carry out the modulation in such a way that it is not perceptible to humans, in order not to impair the function of the light emitting diode as a lamp. A simple example of modulation is light-dark modulation at a frequency of several megahertz. More complex modulations known from radio technology can also be used.
For a single light emitting diode, only a small amount of electrical power needs to be switched. But for realistic room illumination, a plurality of light emitting diodes is needed in order to achieve the necessary light level. In large rooms, it can therefore be assumed that several hundred Watts of electrical power are needed. For data transmission, this would have to be switched at high frequencies of several MHz. However, this can only be achieved with a relatively high level of technical and financial expenditure.